fuel Issues

**scubasteve** · 03-10-2007, 09:33 PM

Well, here is my problem. I have a 95 cobra with a 396ci and a Novi 2000 cog belt set up. I have no inter cooler. The car was put together back in 1997. I have rebuild the motor, transmission, and rear end. I have also replace the fuel pump. The car is has a A9L wired in and tuned by an old school auto logic chip (tuned by Mike Wesley) MY fuel set up is a stock tank with a pick up tube to a automotive fuel pump (good for 1000hp.) It runs threw a filter and -10 to the paxton fuel rails (no y block) basically it goes in on the passenger side then has a line (-10) hooked to the driver side. The return line is -8 and comes off the driver side rail to the fuel regulator (also new). I have 96lbs injectors. My fuel pressure is set about 40psi off vacuum. I have almost all new parts fuel pump, filter, and regulator. I have not replaced any of the lines. The car runs great on cool days (70 or below) but much hotter than that is loses fuel pressure. Today I had the car out and went about 20 miles. The fuel pressure started to drop. With in 30 seconds I it cut off. The fuel pump was still running and the water temperature never got over 185-195. I let the car sit for a while (20-30 minutes) and I could prime the line and get 40psi. Drives for a bit and then again stops pushing fuel. I have noticed the fuel rails are really hot. It acts like vapor lock. I Anyone have any suggestions or experienced the same issues? Is there maybe some newer fuel rails or fuel system I see a lot of you all run a y block? Any help would be great.
Thanks Chad

**Dave Avanti Kid** · 03-11-2007, 12:26 AM

Hi Tominator, Not sure I can help, but hear are some suggestions and a question. What boost are you seeing at your intake manifold from the Novi 2000? Are you near max on blower (55,000 impleller RPM)? On your fuel system going to your EFI system you said that you go from pump to filter then to EFI rails in parallel? then to your one fuel regulator, from reglator excess goes back to tank, is that correct? On my old EFI system with 83 lbs injectors and running the Novi 2000 at 55,000 rpm at 27 lbs (at blower output) boost I have a similar fuel system except at my fuel regulator it has a port for my blower boost to add to my fuel pressure, so as my boost goes up so does my fuel pressure to my EFI system. For example at idle my car fuel pressure is adjusted to 50 lbs, then as my blower boost goes up to 18 lbs (measured at the intake manifold) by fuel pressure goes to 68 lbs. This keeps the fuel system from starving the engine or leaning out. This system worked good for me at WOT for 5 miles at Bonneville with no problem. Also, I found the most important gage is a Wide Band O2 sensor and gage to monitor the engines fuel air ratio, to protect the engine!! Hope this helps you some.
Take care, Dave

**scubasteve** · 03-11-2007, 01:37 AM

I am currently only seeing about 12-15psi. I do have the reg. hooked a vacum line adding fuel pressure like yours. the car is pig rich on the dyno. the problem seams to be a heat issue around the fuel rails and lines. it acts just like a vapor lock on a carb setup.

**Dave Avanti Kid** · 03-11-2007, 08:47 PM

Scubasteve-Chad, In year 2000 with my 1963 Avanti that I raced at Bonneville, it is sponsored by Paxton Automotive products, they gave me a Novi 2000 and helped me get a EFI system from Accel, this system had low impedance 83 lbs/hr injectors which required a amplifer to operate with the ECU (computer) we set it up for 600 hp by adjusting the s/w with a lap top computer and adjusted the pulse width to open the injectors correctly, went on a chassis Dyno for tuning and HP and torque readings. At present since 2001 I had to change from a EFI sytem with the blower to a mechanical fuel injection system made by Airflow Performance Inc. and thinking back to the EFI system I think we hooked it up differently than what you said your system was. We used a Five gallon fuel cell in the trunk went to a Weldon electric fuel pump (good for supporting 1200 hp and 100 psi) then to our fuel filter, then to the fuel regualor, which had a return line going back to the tank and the fuel regulator had a ouput line going to the two fuel rails for the injectors (and fuel pressure gage), and the fuel regulator also had a monitor line coming from the intake manifold to increase the fuel pressure as the blower boost goes up. So our fuel rails were connected differently than yours, could this be a clue of a problem? I'm not an expert in EFI, but that's the way we had ours connected. Now I'm using a mechanical fuel injection the same way as I did the old EFI system. I had to change from EFI to mechanical because I started a new racing class for older muscle cars for Land Speed Racing, these older cars (less aerodynamic than new cars) were Camaros, Mustangs, Chargers, etc from 1981 and older, being older cars before EFI was used we had to use only carbs or mechanical fuel injection for the new class called "Classic". Since then I have done well with it and set world records at Bonnevile at 198.143mph (5 mile course on salt) two way average and at El Mirage Dry Lake a record at 181.019 mph on a dirt race course 1.3 miles long. Question, are any of your fuel lines near the exhaust and are you close to needing to use a intercooler for your blowers output?? My car used to start very easy when I had the EFI system, now with the mechanical system its tricky.
Hope this help some, take care, Dave